package com.huoyun.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.lang.RandomStringUtils;

public class AuthImage extends HttpServlet {

	/**
	 * 
	 */
	private static final long serialVersionUID = 6268361988144833387L;

	private static final int IMAGE_WIDTH = 60;
	
	private static final int IMAGE_HEIGHT = 20;
	
	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException 
	{
        // 取得一个4位随机字母数字字符串  
        String s = RandomStringUtils.random(4, true, true);  
          
        // 保存入session,用于与用户的输入进行比较.  
        // 注意比较完之后清除session.  
        HttpSession session = request.getSession();
        session.setAttribute("verifyCode", s);  
    
        response.setContentType("images/jpeg");  
        response.setHeader("Pragma", "No-cache");  
        response.setHeader("Cache-Control", "no-cache");  
        response.setDateHeader("Expires", 0);  
    
        ServletOutputStream out = response.getOutputStream();  
        BufferedImage image = new BufferedImage(IMAGE_WIDTH, IMAGE_HEIGHT,  
            BufferedImage.TYPE_INT_RGB);  
        Graphics g = image.getGraphics();  
        // 设定背景色  
        g.setColor(getRandColor(200, 250));  
        g.fillRect(0, 0, IMAGE_WIDTH, IMAGE_HEIGHT);  
    
        // 设定字体  
        Font mFont = new Font("Times New Roman", Font.BOLD, 18);// 设置字体  
        g.setFont(mFont);  
    
        // 画边框  
        g.setColor(Color.BLACK);  
        g.drawRect(0, 0, IMAGE_WIDTH - 1, IMAGE_HEIGHT - 1);  
    
        // 随机产生干扰线，使图象中的认证码不易被其它程序探测到  
        g.setColor(getRandColor(160, 200));  
        // 生成随机类  
        Random random = new Random();  
        for (int i = 0; i < 155; i++) {  
          int x2 = random.nextInt(IMAGE_WIDTH);  
          int y2 = random.nextInt(IMAGE_HEIGHT);  
          int x3 = random.nextInt(12);  
          int y3 = random.nextInt(12);  
          g.drawLine(x2, y2, x2 + x3, y2 + y3);  
        }  
    
        // 将认证码显示到图象中  
        g.setColor(new Color(20 + random.nextInt(110), 20 + random  
            .nextInt(110), 20 + random.nextInt(110)));  
    
        g.drawString(s, 2, 16);  
    
        // 图象生效  
        g.dispose();  
        // 输出图象到页面  
        ImageIO.write((BufferedImage) image, "JPEG", out);  
        out.close();  
	}

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException 
	{
		doGet(request, response);
	}

	/**
	 * 给定范围获得随机颜色
	 * @param fc
	 * @param bc
	 * @return
	 */
	private Color getRandColor(int fc, int bc) 
	{   
	      Random random = new Random();  
	      if (fc > 255)  
	        fc = 255;  
	      if (bc > 255)  
	        bc = 255;  
	      int r = fc + random.nextInt(bc - fc);  
	      int g = fc + random.nextInt(bc - fc);  
	      int b = fc + random.nextInt(bc - fc);  
	      return new Color(r, g, b);  
	  }  
}
